The general aim of this project is to obtain a more precise understanding of the role of genetic factors in multiple sclerosis. This will include a number of interrelated questions which will include; (1) determination of histocompatibility types in a carefully selected population of MS patients and appropriate control individuals. (2) Correlation of histocompatibility data in both the patients and controls to the humoral and cell-mediated immune response to measles virus. (3) Evaluation of cerebrospinal fluid immunoglobulin content and specificity in multiple sclerosis patients. (4) Evaluation of families with a multiple incidence in multiple sclerosis and examination of affected and nonaffected members of these families with respect to both histocompatibility makeup and immunological response. (5) Identification of additional lymphocyte antigens which may show a greater degree of correlation with multiple sclerosis than presently identified lymphocyte antigens.